The present invention relates to novel necking pliers adapted for shaping the end of a first pipe which has to be engaged within another pipe initially of same diameter as the first pipe.
The shaping operation for narrowing one end of a pipe is an operation which has to be frequently made in situ when assembling pipe elements for transportation and distribution of air or other gases, typically in air conditioning installations.
For an appropriate assembling of two pipe lengths, it is indispensable that the contraction or necking is made over a notable length, for example a length of pipe in the order of 5 cm.
The force to be exerted so as to contract the metal by corrugating it depends on several factors, in particular hardness of the metal, thickness of the metal, and of course the length along which the contraction has to be made. In all cases, the effort to be applied to the metal is large.